Quasi-colocation indication for demodulation reference signals

ABSTRACT

Certain aspects of the present disclosure provide techniques for signaling quasi-coloration (QCL) information for demodulation reference signals (DM-RS) associated with multiple transmission-reception points (multi-TRP). An example method generally includes generating quasi-colocation (QCL) information indicating a first QCL assumption for a first group of demodulation reference signal (DM-RS) ports and a second QCL assumption for a second group of DM-RS ports; and transmitting the QCL information to at least one user equipment (UE) for use in processing one or more transmission associated with at least one of the first group of DM-RS ports and the second group of DM-RS ports.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a national stage application under 35 U.S.C. 371 ofPCT/CN2019/099023, filed Aug. 2, 2019, which claims benefit and priorityto International Application No. PCT/CN2018/099894, filed Aug. 10, 2018,both of which are herein incorporated by reference herein in theirentireties for all applicable purposes.

BACKGROUND Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, andmore particularly, to techniques for signaling quasi-colocation (QCL)information for demodulation reference signals (DM-RS) associated withmultiple transmission-reception points (multi-TRP).

Description of Related Art

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,broadcasts, etc. These wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power, etc.). Examples of such multiple-access systems include3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE)systems, LTE Advanced (LTE-A) systems, code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems, to name a few.

In some examples, a wireless multiple-access communication system mayinclude a number of base stations (BSs), which are each capable ofsimultaneously supporting communication for multiple communicationdevices, otherwise known as user equipments (UEs). In an LTE or LTE-Anetwork, a set of one or more base stations may define an eNodeB (eNB).In other examples (e.g., in a next generation, a new radio (NR), or 5Gnetwork), a wireless multiple access communication system may include anumber of distributed units (DUs) (e.g., edge units (EUs), edge nodes(ENs), radio heads (RHs), smart radio heads (SRHs), transmissionreception points (TRPs), etc.) in communication with a number of centralunits (CUs) (e.g., central nodes (CNs), access node controllers (ANCs),etc.), where a set of one or more distributed units, in communicationwith a central unit, may define an access node (e.g., which may bereferred to as a base station, 5G NB, next generation NodeB (gNB orgNodeB), TRP, etc.). A base station or distributed unit may communicatewith a set of UEs on downlink channels (e.g., for transmissions from abase station or to a UE) and uplink channels (e.g., for transmissionsfrom a UE to a base station or distributed unit).

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. New Radio (NR) (e.g., 5G) is an exampleof an emerging telecommunication standard. NR is a set of enhancementsto the LTE mobile standard promulgated by 3GPP. It is designed to bettersupport mobile broadband Internet access by improving spectralefficiency, lowering costs, improving services, making use of newspectrum, and better integrating with other open standards using OFDMAwith a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL).To these ends, NR supports beamforming, multiple-input multiple-output(MIMO) antenna technology, and carrier aggregation.

However, as the demand for mobile broadband access continues toincrease, there exists a need for further improvements in NR and LTEtechnology. Preferably, these improvements should be applicable to othermulti-access technologies and the telecommunication standards thatemploy these technologies.

SUMMARY

The systems, methods, and devices of the disclosure each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this disclosure as expressedby the claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “Detailed Description” one will understand how thefeatures of this disclosure provide advantages that include improvedcommunications between a base station and user equipment in a wirelessnetwork.

Certain aspects provide a method for wireless communication by a basestation (BS). The method generally includes generating quasi-colocation(QCL) information indicating a first QCL assumption for a first group ofdemodulation reference signal (DM-RS) ports and a second QCL assumptionfor a second group of DM-RS ports; and transmitting the QCL informationto at least one user equipment (UE) for use in processing one or moretransmission associated with at least one of the first group of DM-RSports and the second group of DM-RS ports.

Certain aspects provide a method for wireless communication by a userequipment (UE). The method generally includes obtaining quasi-colocation(QCL) information indicating a first QCL assumption for a first group ofdemodulation reference signal (DM-RS) ports and a second QCL assumptionfor a second group of DM-RS ports; and receiving transmissionsassociated with the first group of DM-RS ports and the second group ofDM-RS ports based on the QCL information.

Aspects of the present disclosure also provide various apparatuses,means, and computer program products corresponding to the methods andoperations described above.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe appended drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the drawings. It is to be noted, however, thatthe appended drawings illustrate only certain typical aspects of thisdisclosure and are therefore not to be considered limiting of its scope,for the description may admit to other equally effective aspects.

FIG. 1 is a block diagram conceptually illustrating an exampletelecommunications system, in accordance with certain aspects of thepresent disclosure.

FIG. 2 is a block diagram illustrating an example logical architectureof a distributed radio access network (RAN), in accordance with certainaspects of the present disclosure.

FIG. 3 is a diagram illustrating an example physical architecture of adistributed RAN, in accordance with certain aspects of the presentdisclosure.

FIG. 4 is a block diagram conceptually illustrating a design of anexample base station (BS) and user equipment (UE), in accordance withcertain aspects of the present disclosure.

FIG. 5 is a diagram showing examples for implementing a communicationprotocol stack, in accordance with certain aspects of the presentdisclosure.

FIG. 6 illustrates an example of a frame format for a new radio (NR)system, in accordance with certain aspects of the present disclosure.

FIG. 7 illustrates an example transmission configuration indicator (TCI)state, in accordance with certain aspects of the present disclosure.

FIG. 8 illustrates an example of QCL information, in accordance withcertain aspects of the present disclosure.

FIG. 9 is a flow diagram illustrating example operations for configuringDM-RS transmissions with QCL information that supports multi-TRPtransmissions, in accordance with certain aspects of the presentdisclosure.

FIG. 10 is a flow diagram illustrating example operations forconfiguring DM-RS transmissions with QCL information that supportsmulti-TRP transmissions, in accordance with certain aspects of thepresent disclosure.

FIG. 11 illustrates an example transmission configuration indicator(TCI) state, in accordance with certain aspects of the presentdisclosure.

FIG. 12 illustrates a communications device that may include variouscomponents configured to perform operations for the techniques disclosedherein in accordance with aspects of the present disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in one aspectmay be beneficially utilized on other aspects without specificrecitation.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processingsystems, and computer readable mediums for signaling quasi-colocation(QCL) information for demodulation reference signals (DM-RS) associatedwith multiple transmission-reception points (multi-TRP) or multipleantenna panels (multi-panel). Aspects of the present disclosure providesignaling, to a UE, QCL assumptions linked to multiple antenna portgroups. For example, a UE may receive, from a BS, QCL informationassociated with multiple antenna groups, and the UE may apply the QCLassumptions to receive transmissions via the multiple antenna portgroups such as multi-TRP/multi-panel transmissions.

The following description provides examples, and is not limiting of thescope, applicability, or examples set forth in the claims. Changes maybe made in the function and arrangement of elements discussed withoutdeparting from the scope of the disclosure. Various examples may omit,substitute, or add various procedures or components as appropriate. Forinstance, the methods described may be performed in an order differentfrom that described, and various steps may be added, omitted, orcombined. Also, features described with respect to some examples may becombined in some other examples. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition to,or other than, the various aspects of the disclosure set forth herein.It should be understood that any aspect of the disclosure disclosedherein may be embodied by one or more elements of a claim. The word“exemplary” is used herein to mean “serving as an example, instance, orillustration.” Any aspect described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otheraspects.

The techniques described herein may be used for various wirelesscommunication technologies, such as LTE, CDMA, TDMA, FDMA, OFDMA,SC-FDMA and other networks. The terms “network” and “system” are oftenused interchangeably. A CDMA network may implement a radio technologysuch as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRAincludes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implementa radio technology such as Global System for Mobile Communications(GSM). An OFDMA network may implement a radio technology such as NR(e.g. 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRAand E-UTRA are part of Universal Mobile Telecommunication System (UMTS).

New Radio (NR) is an emerging wireless communications technology underdevelopment in conjunction with the 5G Technology Forum (5GTF). 3GPPLong Term Evolution (LTE) and LTE-Advanced (LTE-A) are releases of UMTSthat use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described indocuments from an organization named “3rd Generation PartnershipProject” (3GPP). cdma2000 and UMB are described in documents from anorganization named “3rd Generation Partnership Project 2” (3GPP2). Thetechniques described herein may be used for the wireless networks andradio technologies mentioned above as well as other wireless networksand radio technologies. For clarity, while aspects may be describedherein using terminology commonly associated with 3G and/or 4G wirelesstechnologies, aspects of the present disclosure can be applied in othergeneration-based communication systems, such as 5G and later, includingNR technologies.

New radio (NR) access (e.g., 5G technology) may support various wirelesscommunication services, such as enhanced mobile broadband (eMBB)targeting wide bandwidth (e.g., 80 MHz or beyond), millimeter wave (mmW)targeting high carrier frequency (e.g., 25 GHz or beyond), massivemachine type communications MTC (mMTC) targeting non-backward compatibleMTC techniques, and/or mission critical targeting ultra-reliablelow-latency communications (URLLC). These services may include latencyand reliability requirements. These services may also have differenttransmission time intervals (TTI) to meet respective quality of service(QoS) requirements. In addition, these services may co-exist in the samesubframe.

Example Wireless Communications System

FIG. 1 illustrates an example wireless communication network 100 inwhich aspects of the present disclosure may be performed. The wirelesscommunication network 100 may be a New Radio (NR) or 5G network thatsupports multiple DM-RS port groups for QCL assumptions. For example, UE120 a may receive, from BS 110 a, QCL information corresponding tomultiple antenna groups, such as demodulation reference signal (DM-RS)port groups. The QCL information may enable the UE 120 a to apply QCLassumptions to multi-TRP/multi-panel transmissions, such astransmissions from BS 110 a and BS 110 b or transmissions from multipleantenna panels of BS 110 a.

As illustrated in FIG. 1 , the wireless network 100 may include a numberof base stations (BSs) 110 and other network entities. A BS may be astation that communicates with user equipments (UEs). Each BS 110 mayprovide communication coverage for a particular geographic area. In3GPP, the term “cell” can refer to a coverage area of a Node B (NB)and/or a Node B subsystem serving this coverage area, depending on thecontext in which the term is used. In NR systems, the term “cell” andnext generation NodeB (gNB), new radio base station (NR BS), 5G NB,access point (AP), or transmission reception point (TRP) may beinterchangeable. In some examples, a cell may not necessarily bestationary, and the geographic area of the cell may move according tothe location of a mobile BS. In some examples, the base stations may beinterconnected to one another and/or to one or more other base stationsor network nodes (not shown) in wireless communication network 100through various types of backhaul interfaces, such as a direct physicalconnection, a wireless connection, a virtual network, or the like usingany suitable transport network.

In general, any number of wireless networks may be deployed in a givengeographic area. Each wireless network may support a particular radioaccess technology (RAT) and may operate on one or more frequencies. ARAT may also be referred to as a radio technology, an air interface,etc. A frequency may also be referred to as a carrier, a subcarrier, afrequency channel, a tone, a subband, etc. Each frequency may support asingle RAT in a given geographic area in order to avoid interferencebetween wireless networks of different RATs. In some cases, NR or 5G RATnetworks may be deployed.

A base station (BS) may provide communication coverage for a macro cell,a pico cell, a femto cell, and/or other types of cells. A macro cell maycover a relatively large geographic area (e.g., several kilometers inradius) and may allow unrestricted access by UEs with servicesubscription. A pico cell may cover a relatively small geographic areaand may allow unrestricted access by UEs with service subscription. Afemto cell may cover a relatively small geographic area (e.g., a home)and may allow restricted access by UEs having an association with thefemto cell (e.g., UEs in a Closed Subscriber Group (CSG), UEs for usersin the home, etc.). A BS for a macro cell may be referred to as a macroBS. A BS for a pico cell may be referred to as a pico BS. ABS for afemto cell may be referred to as a femto BS or a home BS. In the exampleshown in FIG. 1 , the BSs 110 a, 110 b and 110 c may be macro BSs forthe macro cells 102 a, 102 b and 102 c, respectively. The BS 110 x maybe a pico BS for a pico cell 102 x. The BSs 110 y and 110 z may be femtoBSs for the femto cells 102 y and 102 z, respectively. A BS may supportone or multiple (e.g., three) cells.

Wireless communication network 100 may also include relay stations. Arelay station is a station that receives a transmission of data and/orother information from an upstream station (e.g., a BS or a UE) andsends a transmission of the data and/or other information to adownstream station (e.g., a UE or a BS). A relay station may also be aUE that relays transmissions for other UEs. In the example shown in FIG.1 , a relay station 110 r may communicate with the BS 110 a and a UE 120r in order to facilitate communication between the BS 110 a and the UE120 r. A relay station may also be referred to as a relay BS, a relay,etc.

Wireless network 100 may be a heterogeneous network that includes BSs ofdifferent types, e.g., macro BS, pico BS, femto BS, relays, etc. Thesedifferent types of BSs may have different transmit power levels,different coverage areas, and different impact on interference in thewireless network 100. For example, macro BS may have a high transmitpower level (e.g., 20 Watts) whereas pico BS, femto BS, and relays mayhave a lower transmit power level (e.g., 1 Watt).

Wireless communication network 100 may support synchronous orasynchronous operation. For synchronous operation, the BSs may havesimilar frame timing, and transmissions from different BSs may beapproximately aligned in time. For asynchronous operation, the BSs mayhave different frame timing, and transmissions from different BSs maynot be aligned in time. The techniques described herein may be used forboth synchronous and asynchronous operation.

A network controller 130 may couple to a set of BSs and providecoordination and control for these BSs. The network controller 130 maycommunicate with the BSs 110 via a backhaul. The BSs 110 may alsocommunicate with one another (e.g., directly or indirectly) via wirelessor wireline backhaul.

The UEs 120 (e.g., 120 x, 120 y, etc.) may be dispersed throughout thewireless network 100, and each UE may be stationary or mobile. A UE mayalso be referred to as a mobile station, a terminal, an access terminal,a subscriber unit, a station, a Customer Premises Equipment (CPE), acellular phone, a smart phone, a personal digital assistant (PDA), awireless modem, a wireless communication device, a handheld device, alaptop computer, a cordless phone, a wireless local loop (WLL) station,a tablet computer, a camera, a gaming device, a netbook, a smartbook, anultrabook, an appliance, a medical device or medical equipment, abiometric sensor/device, a wearable device such as a smart watch, smartclothing, smart glasses, a smart wrist band, smart jewelry (e.g., asmart ring, a smart bracelet, etc.), an entertainment device (e.g., amusic device, a video device, a satellite radio, etc.), a vehicularcomponent or sensor, a smart meter/sensor, industrial manufacturingequipment, a global positioning system device, or any other suitabledevice that is configured to communicate via a wireless or wired medium.Some UEs may be considered machine-type communication (MTC) devices orevolved MTC (eMTC) devices. MTC and eMTC UEs include, for example,robots, drones, remote devices, sensors, meters, monitors, locationtags, etc., that may communicate with a BS, another device (e.g., remotedevice), or some other entity. A wireless node may provide, for example,connectivity for or to a network (e.g., a wide area network such asInternet or a cellular network) via a wired or wireless communicationlink. Some UEs may be considered Internet-of-Things (IoT) devices, whichmay be narrowband IoT (NB-IoT) devices.

Certain wireless networks (e.g., LTE) utilize orthogonal frequencydivision multiplexing (OFDM) on the downlink and single-carrierfrequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDMpartition the system bandwidth into multiple (K) orthogonal subcarriers,which are also commonly referred to as tones, bins, etc. Each subcarriermay be modulated with data. In general, modulation symbols are sent inthe frequency domain with OFDM and in the time domain with SC-FDM. Thespacing between adjacent subcarriers may be fixed, and the total numberof subcarriers (K) may be dependent on the system bandwidth. Forexample, the spacing of the subcarriers may be 15 kHz and the minimumresource allocation (called a “resource block” (RB)) may be 12subcarriers (or 180 kHz). Consequently, the nominal Fast FourierTransfer (FFT) size may be equal to 128, 256, 512, 1024 or 2048 forsystem bandwidth of 1.25, 2.5, 5, 10, or 20 megahertz (MHz),respectively. The system bandwidth may also be partitioned intosubbands. For example, a subband may cover 1.08 MHz (i.e., 6 resourceblocks), and there may be 1, 2, 4, 8, or 16 subbands for systembandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

While aspects of the examples described herein may be associated withLTE technologies, aspects of the present disclosure may be applicablewith other wireless communications systems, such as NR. NR may utilizeOFDM with a cyclic prefix (CP) on the uplink and downlink and includesupport for half-duplex operation using TDD. Beamforming may besupported and beam direction may be dynamically configured. MIMOtransmissions with precoding may also be supported. MIMO configurationsin the DL may support up to 8 transmit antennas with multi-layer DLtransmissions up to 8 streams and up to 2 streams per UE. Aggregation ofmultiple cells may be supported with up to 8 serving cells.

In some examples, access to the air interface may be scheduled, whereina scheduling entity (e.g., a base station) allocates resources forcommunication among some or all devices and equipment within its servicearea or cell. The scheduling entity may be responsible for scheduling,assigning, reconfiguring, and releasing resources for one or moresubordinate entities. That is, for scheduled communication, subordinateentities utilize resources allocated by the scheduling entity. Basestations are not the only entities that may function as a schedulingentity. In some examples, a UE may function as a scheduling entity andmay schedule resources for one or more subordinate entities (e.g., oneor more other UEs), and the other UEs may utilize the resourcesscheduled by the UE for wireless communication. In some examples, a UEmay function as a scheduling entity in a peer-to-peer (P2P) network,and/or in a mesh network. In a mesh network example, UEs may communicatedirectly with one another in addition to communicating with a schedulingentity.

In FIG. 1 , a solid line with double arrows indicates desiredtransmissions between a UE and a serving BS, which is a BS designated toserve the UE on the downlink and/or uplink. A finely dashed line withdouble arrows indicates interfering transmissions between a UE and a BS.

FIG. 2 illustrates an example logical architecture of a distributedRadio Access Network (RAN) 200, which may be implemented in the wirelesscommunication network 100 illustrated in FIG. 1 . A 5G access node 206may include an access node controller (ANC) 202. ANC 202 may be acentral unit (CU) of the distributed RAN 200. The backhaul interface tothe Next Generation Core Network (NG-CN) 204 may terminate at ANC 202.The backhaul interface to neighboring next generation access Nodes(NG-ANs) 210 may terminate at ANC 202. ANC 202 may include one or moretransmission reception points (TRPs) 208 (e.g., cells, BSs, gNBs, etc.).

The TRPs 208 may be a distributed unit (DU). TRPs 208 may be connectedto a single ANC (e.g., ANC 202) or more than one ANC (not illustrated).For example, for RAN sharing, radio as a service (RaaS), and servicespecific AND deployments, TRPs 208 may be connected to more than oneANC. TRPs 208 may each include one or more antenna ports. TRPs 208 maybe configured to individually (e.g., dynamic selection) or jointly(e.g., joint transmission) serve traffic to a UE.

The logical architecture of distributed RAN 200 may support fronthaulingsolutions across different deployment types. For example, the logicalarchitecture may be based on transmit network capabilities (e.g.,bandwidth, latency, and/or jitter).

The logical architecture of distributed RAN 200 may share featuresand/or components with LTE. For example, next generation access node(NG-AN) 210 may support dual connectivity with NR and may share a commonfronthaul for LTE and NR.

The logical architecture of distributed RAN 200 may enable cooperationbetween and among TRPs 208, for example, within a TRP and/or across TRPsvia ANC 202. An inter-TRP interface may not be used.

Logical functions may be dynamically distributed in the logicalarchitecture of distributed RAN 200. As will be described in more detailwith reference to FIG. 5 , the Radio Resource Control (RRC) layer,Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC)layer, Medium Access Control (MAC) layer, and a Physical (PHY) layersmay be adaptably placed at the DU (e.g., TRP 208) or CU (e.g., ANC 202).

FIG. 3 illustrates an example physical architecture of a distributedRadio Access Network (RAN) 300, according to aspects of the presentdisclosure. A centralized core network unit (C-CU) 302 may host corenetwork functions. C-CU 302 may be centrally deployed. C-CU 302functionality may be offloaded (e.g., to advanced wireless services(AWS)), in an effort to handle peak capacity.

A centralized RAN unit (C-RU) 304 may host one or more ANC functions.Optionally, the C-RU 304 may host core network functions locally. TheC-RU 304 may have distributed deployment. The C-RU 304 may be close tothe network edge.

A DU 306 may host one or more TRPs (Edge Node (EN), an Edge Unit (EU), aRadio Head (RH), a Smart Radio Head (SRH), or the like). The DU may belocated at edges of the network with radio frequency (RF) functionality.

FIG. 4 illustrates example components of BS 110 and UE 120 (as depictedin FIG. 1 ), which may be used to implement aspects of the presentdisclosure. For example, antennas 452, processors 466, 458, 464, and/orcontroller/processor 480 of the UE 120 and/or antennas 434, processors420, 430, 438, and/or controller/processor 440 of the BS 110 may be usedto perform the various techniques and methods described herein (FIGS. 9and 10 ). For example, UE 120 may receive, from BS 110, QCL informationcorresponding to multiple antenna groups, such as demodulation DM-RSport groups. The QCL information may enable the UE 120 to apply QCLassumptions to receive transmissions via the multiple antenna portgroups, such as multi-TRP/multi-panel transmissions.

At the BS 110, a transmit processor 420 may receive data from a datasource 412 and control information from a controller/processor 440. Thecontrol information may be for the physical broadcast channel (PBCH),physical control format indicator channel (PCFICH), physical hybrid ARQindicator channel (PHICH), physical downlink control channel (PDCCH),group common PDCCH (GC PDCCH), etc. The data may be for the physicaldownlink shared channel (PDSCH), etc. The processor 420 may process(e.g., encode and symbol map) the data and control information to obtaindata symbols and control symbols, respectively. The processor 420 mayalso generate reference symbols, e.g., for the primary synchronizationsignal (PSS), secondary synchronization signal (SSS), and cell-specificreference signal (CRS). A transmit (TX) multiple-input multiple-output(MIMO) processor 430 may perform spatial processing (e.g., precoding) onthe data symbols, the control symbols, and/or the reference symbols, ifapplicable, and may provide output symbol streams to the modulators(MODs) 432 a through 432 t. Each modulator 432 may process a respectiveoutput symbol stream (e.g., for OFDM, etc.) to obtain an output samplestream. Each modulator may further process (e.g., convert to analog,amplify, filter, and upconvert) the output sample stream to obtain adownlink signal. Downlink signals from modulators 432 a through 432 tmay be transmitted via the antennas 434 a through 434 t, respectively.

At the UE 120, the antennas 452 a through 452 r may receive the downlinksignals from the base station 110 and may provide received signals tothe demodulators (DEMODs) in transceivers 454 a through 454 r,respectively. Each demodulator 454 may condition (e.g., filter, amplify,downconvert, and digitize) a respective received signal to obtain inputsamples. Each demodulator may further process the input samples (e.g.,for OFDM, etc.) to obtain received symbols. A MIMO detector 456 mayobtain received symbols from all the demodulators 454 a through 454 r,perform MIMO detection on the received symbols if applicable, andprovide detected symbols. A receive processor 458 may process (e.g.,demodulate, deinterleave, and decode) the detected symbols, providedecoded data for the UE 120 to a data sink 460, and provide decodedcontrol information to a controller/processor 480.

On the uplink, at UE 120, a transmit processor 464 may receive andprocess data (e.g., for the physical uplink shared channel (PUSCH)) froma data source 462 and control information (e.g., for the physical uplinkcontrol channel (PUCCH) from the controller/processor 480. The transmitprocessor 464 may also generate reference symbols for a reference signal(e.g., for the sounding reference signal (SRS)). The symbols from thetransmit processor 464 may be precoded by a TX MIMO processor 466 ifapplicable, further processed by the demodulators in transceivers 454 athrough 454 r (e.g., for SC-FDM, etc.), and transmitted to the basestation 110. At the BS 110, the uplink signals from the UE 120 may bereceived by the antennas 434, processed by the modulators 432, detectedby a MIMO detector 436 if applicable, and further processed by a receiveprocessor 438 to obtain decoded data and control information sent by theUE 120. The receive processor 438 may provide the decoded data to a datasink 439 and the decoded control information to the controller/processor440.

The controllers/processors 440 and 480 may direct the operation at thebase station 110 and the UE 120, respectively. The processor 440 and/orother processors and modules at the BS 110 may perform or direct theexecution of processes for the techniques described herein. The memories442 and 482 may store data and program codes for BS 110 and UE 120,respectively. A scheduler 444 may schedule UEs for data transmission onthe downlink and/or uplink.

FIG. 5 illustrates a diagram 500 showing examples for implementing acommunications protocol stack, according to aspects of the presentdisclosure. The illustrated communications protocol stacks may beimplemented by devices operating in a wireless communication system,such as a 5G system (e.g., a system that supports uplink-basedmobility). Diagram 500 illustrates a communications protocol stackincluding a Radio Resource Control (RRC) layer 510, a Packet DataConvergence Protocol (PDCP) layer 515, a Radio Link Control (RLC) layer520, a Medium Access Control (MAC) layer 525, and a Physical (PHY) layer530. In various examples, the layers of a protocol stack may beimplemented as separate modules of software, portions of a processor orASIC, portions of non-collocated devices connected by a communicationslink, or various combinations thereof. Collocated and non-collocatedimplementations may be used, for example, in a protocol stack for anetwork access device (e.g., ANs, CUs, and/or DUs) or a UE.

A first option 505-a shows a split implementation of a protocol stack,in which implementation of the protocol stack is split between acentralized network access device (e.g., an ANC 202 in FIG. 2 ) anddistributed network access device (e.g., DU 208 in FIG. 2 ). In thefirst option 505-a, an RRC layer 510 and a PDCP layer 515 may beimplemented by the central unit, and an RLC layer 520, a MAC layer 525,and a PHY layer 530 may be implemented by the DU. In various examplesthe CU and the DU may be collocated or non-collocated. The first option505-a may be useful in a macro cell, micro cell, or pico celldeployment.

A second option 505-b shows a unified implementation of a protocolstack, in which the protocol stack is implemented in a single networkaccess device. In the second option, RRC layer 510, PDCP layer 515, RLClayer 520, MAC layer 525, and PHY layer 530 may each be implemented bythe AN. The second option 505-b may be useful in, for example, a femtocell deployment.

Regardless of whether a network access device implements part or all ofa protocol stack, a UE may implement an entire protocol stack as shownin 505-c (e.g., the RRC layer 510, the PDCP layer 515, the RLC layer520, the MAC layer 525, and the PHY layer 530).

In LTE, the basic transmission time interval (TTI) or packet duration isthe 1 ms subframe. In NR, a subframe is still 1 ms, but the basic TTI isreferred to as a slot. A subframe contains a variable number of slots(e.g., 1, 2, 4, 8, 16, . . . slots) depending on the subcarrier spacing.The NR RB is 12 consecutive frequency subcarriers. NR may support a basesubcarrier spacing of 15 KHz and other subcarrier spacing may be definedwith respect to the base subcarrier spacing, for example, 30 kHz, 60kHz, 120 kHz, 240 kHz, etc. The symbol and slot lengths scale with thesubcarrier spacing. The CP length also depends on the subcarrierspacing.

FIG. 6 is a diagram showing an example of a frame format 600 for NR. Thetransmission timeline for each of the downlink and uplink may bepartitioned into units of radio frames. Each radio frame may have apredetermined duration (e.g., 10 ms) and may be partitioned into 10subframes, each of 1 ms, with indices of 0 through 9. Each subframe mayinclude a variable number of slots depending on the subcarrier spacing.Each slot may include a variable number of symbol periods (e.g., 7, 12,or 14 symbols) depending on the subcarrier spacing. The symbol periodsin each slot may be assigned indices. A mini-slot, which may be referredto as a sub-slot structure, refers to a transmit time interval having aduration less than a slot (e.g., 2, 3, or 4 symbols).

Each symbol in a slot may indicate a link direction (e.g., DL, UL, orflexible) for data transmission and the link direction for each subframemay be dynamically switched. The link directions may be based on theslot format. Each slot may include DL/UL data as well as DL/UL controlinformation.

In NR, a synchronization signal (SS) block is transmitted. The SS blockincludes a PSS, a SSS, and a two symbol PBCH. The SS block can betransmitted in a fixed slot location, such as the symbols 0-3 as shownin FIG. 6 . The PSS and SSS may be used by UEs for cell search andacquisition. The PSS may provide half-frame timing, the SS may providethe CP length and frame timing. The PSS and SSS may provide the cellidentity. The PBCH carries some basic system information, such asdownlink system bandwidth, timing information within radio frame, SSburst set periodicity, system frame number, etc. The SS blocks may beorganized into SS bursts to support beam sweeping. Further systeminformation such as, remaining minimum system information (RMSI), systeminformation blocks (SIBs), other system information (OSI) can betransmitted on a physical downlink shared channel (PDSCH) in certainsubframes.

In some circumstances, two or more subordinate entities (e.g., UEs) maycommunicate with each other using sidelink signals. Real-worldapplications of such sidelink communications may include public safety,proximity services, UE-to-network relaying, vehicle-to-vehicle (V2V)communications, Internet of Everything (IoE) communications, IoTcommunications, mission-critical mesh, and/or various other suitableapplications. Generally, a sidelink signal may refer to a signalcommunicated from one subordinate entity (e.g., UE1) to anothersubordinate entity (e.g., UE2) without relaying that communicationthrough the scheduling entity (e.g., UE or BS), even though thescheduling entity may be utilized for scheduling and/or controlpurposes. In some examples, the sidelink signals may be communicatedusing a licensed spectrum (unlike wireless local area networks, whichtypically use an unlicensed spectrum).

A UE may operate in various radio resource configurations, including aconfiguration associated with transmitting pilots using a dedicated setof resources (e.g., a radio resource control (RRC) dedicated state,etc.) or a configuration associated with transmitting pilots using acommon set of resources (e.g., an RRC common state, etc.). Whenoperating in the RRC dedicated state, the UE may select a dedicated setof resources for transmitting a pilot signal to a network. Whenoperating in the RRC common state, the UE may select a common set ofresources for transmitting a pilot signal to the network. In eithercase, a pilot signal transmitted by the UE may be received by one ormore network access devices, such as an AN, or a DU, or portionsthereof. Each receiving network access device may be configured toreceive and measure pilot signals transmitted on the common set ofresources, and also receive and measure pilot signals transmitted ondedicated sets of resources allocated to the UEs for which the networkaccess device is a member of a monitoring set of network access devicesfor the UE. One or more of the receiving network access devices, or a CUto which receiving network access device(s) transmit the measurements ofthe pilot signals, may use the measurements to identify serving cellsfor the UEs, or to initiate a change of serving cell for one or more ofthe UEs.

Example Quasi-Colocation Indication for Demodulation Reference Signals

Aspects of the present disclosure provide techniques for providingquasi-colocation (QCL) signaling for groups of demodulation referencesignal (DM-RS) ports across scenarios involving multiple cells and/ormultiple panels (multi-panel), such as coordinated multipoint (CoMP)scenarios in which a UE is connected to multiple transmit receive points(TRPs).

QCL assumptions generally refer to assumptions that, for a set ofsignals or channels considered to be QCL related (or simply “QCL′d” forshort), certain characteristics derived for (measured from) one of thesignals or channels may be applied to the other. As an example, if PDSCHDMRS is QCL′d with other DL RS, a UE may process PDSCH and measure theassociated DM-RS based on characteristics/measurements of the other DLRS.

In some cases, QCL assumptions for receptions/transmissions of signalsand channels may be signaled via a mechanism referred to as TransmissionConfiguration Indicator (TCI) states. FIG. 7 illustrates an example TCIstate used to configure a DM-RS port group via control signaling, inaccordance with certain aspects of the present disclosure. In thisexample, the TCI state includes a single QCL configuration having atleast two types of QCL information, which may provide QCL assumptionsfor two different DL reference signals. In some cases, a UE may beconfigured with various TCI states via radio resource control (RRC)signaling, while one of the actual TCI states may be indicated by an Nbit DCI field for PDSCH. In some other cases, a UE may be configuredwith a subset of various TCI states (e.g., up to 8 TCI states) via MACcontrol signaling (e.g., a MAC control element (MAC-CE)), and downlinkcontrol signaling (e.g., DCI) may be used to select a TCI state out ofthe subset (e.g., 3 bits may be used to identify which TCI state isenabled).

FIG. 8 illustrates an example of QCL information that may be included ina QCL configuration, in accordance with certain aspects of the presentdisclosure. The QCL assumptions may be grouped into different types thatcorrespond to the parameters that may be assumed QCL′d for a set ofQCL′d signals. For example, for a set of QCL′d signals, Type A mayindicate that Doppler shift, Doppler spread, average delay, delay spreadcan be assumed QCL′d, while Type B may indicate only Doppler shift andDoppler spread, Type C may indicate a still different set of parameters.In some cases, spatial QCL assumptions may be indicated, for example, byType D. Spatial QCL may mean a (Tx or Rx) beam selected based on acertain signal measurement may be applied to the QCL related signal. Asan example, the QCL assumptions may provide a QCL relationship between aDM-RS and at least one of a channel state information reference signal(CSI-RS) or a synchronization signal (SS). As used herein, a set ofQCL′d signals refers to the QCL relationship between those signals(e.g., Doppler shift, Doppler spread, average delay, and/or delayspread).

One limitation of the current QCL configuration is that only one TCIstate consisting of a single QCL assumption is provided per DLtransmission. That is, all the DM-RS ports have the same QCLassumptions. In some cases, multiple DM-RS port groups are configuredfor a DL transmission, but the current QCL configuration only supportssignaling of a single QCL assumption. Aspects of the present disclosure,however, extend the QCL configuration to allow signaling of QCLassumptions linked to multiple antenna port groups. As such, the QCLsignaling described herein may be applied in multi-TRP/multi-panelscenarios, such as CoMP deployments where multiple transmissionreception points (TRPs) communicate with a UE.

FIG. 9 is a flow diagram illustrating example operations 900 that may beperformed, for example, by a base station (e.g., BS 110), forconfiguring DM-RS transmissions with QCL information that supportsmulti-TRP transmissions, in accordance with certain aspects of thepresent disclosure.

Operations 900 may begin, at 902, where the BS generatesquasi-colocation (QCL) information indicating a first QCL assumption fora first group of demodulation reference signal (DM-RS) ports and asecond QCL assumption for a second group of DM-RS ports. At 904, the BStransmits the QCL information to at least one user equipment (UE) foruse in processing one or more transmission associated with at least oneof the first group of DM-RS ports and the second group of DM-RS ports.

FIG. 10 is a flow diagram illustrating example operations 1000 that maybe performed, for example, by a user equipment (e.g., UE 120), forconfiguring DM-RS transmissions with QCL information that supportsmulti-TRP/multi-panel transmissions, in accordance with certain aspectsof the present disclosure.

Operations 1000 may begin, at 1002, where the UE obtainsquasi-colocation (QCL) information indicating a first QCL assumption fora first group of demodulation reference signal (DM-RS) ports and asecond QCL assumption for a second group of DM-RS ports. At 1004, the UEreceives transmissions associated with the first group of DM-RS portsand the second group of DM-RS ports based on the QCL information.

The QCL information may be transmitted to the UE via control signalingsuch as radio resource control (RRC) signaling (e.g., RRC element),medium access control (MAC) signaling (e.g., MAC control element(MAC-CE)), or downlink control signaling (e.g., downlink controlinformation (DCI)). For example, the UE may be initially configured withvarious TCI states (e.g., up to 8 TCI states per DL transmission) viaRRC signaling, and DCI signaling may be used to select one or more ofthe TCI states (e.g., 6 bits may be used to select the TCI states usedfor the DL transmissions). The UE may determine QCL assumptionsassociated with the DM-RS port groups based on the QCL informationsignaled to the UE. The UE may then monitor and receive transmissionsassociated with the DM-RS port groups based on the QCL assumptions.

In certain aspects, the QCL information may be indicated via a TCI statehaving at least a first QCL configuration and a second QCLconfiguration. FIG. 11 illustrates an example TCI state used toconfigure DM-RS port groups via control signaling, in accordance withcertain aspects of the present disclosure. As illustrated in FIG. 11 ,the TCI state may provide the QCL assumptions for at least two DM-RSport groups. For example, the UE may assume that the first QCLconfiguration (qcl-Config1) provides the QCL assumptions for the firstgroup of DM-RS ports, and that the second QCL configuration(qcl-Config2) provides the QCL assumptions for the second group of DM-RSports. In situations where one of the QCL configuration provides no QCLinformation (i.e., the field is reserved), the first QCL configurationmay be applied to the QCL assumptions for the first and second group ofDM-RS ports, or vice versa. In other aspects, the first QCLconfiguration may be applied to the QCL assumptions for the first groupof DM-RS ports, and a default QCL configuration may be applied to theQCL assumptions for the second group of DM-RS ports, or vice versa.

If the UE is configured with only one DM-RS port group, all the portsare QCL′d with the same QCL information in the TCI state. As examples,if the UE obtains only one QCL configuration, then that QCLconfiguration is applied to the configured DM-RS port group. If the UEobtains two QCL configurations, then the UE may apply the first QCLconfiguration to the configured DM-RS port group. In other aspects, theUE may apply the QCL configuration based on the index of the DM-RS portgroup. For example, if the configured DM-RS port group has an indexindicating that it is the first DM-RS port group, the UE may apply thefirst QCL configuration to the configured DM-RS port group, and if theconfigured DM-RS port group has an index indicating that it is thesecond DM-RS port group, then the UE may apply the second QCLconfiguration to the configured DM-RS port group.

For aspects, the QCL information may be indicated via a plurality of TCIstates, and each of the TCI states comprises a QCL configuration. Forexample, the TCI state shown in FIG. 7 may be used as one of theplurality of TCI states. As an example, an indication having theplurality of TCI states, each of the TCI states having a QCLconfiguration associated with a DM-RS port group, may be signaled, bythe BS, to the UE via a control message, such as a RRC message, MAC-CEmessage, or DCI message. That is, the plurality of TCI states supportingmulti-TRP/multi-panel transmissions may be signaled via a singleindicator included in a control message transmitted to the UE. The UEmay receive the control message having the TCI states and determine theQCL assumptions for the DM-RS port groups based on the TCI states.

For aspects, the QCL information may be indicated via a TCI state havinga single QCL configuration. The UE may assume that the QCL configurationapplies to the QCL assumptions for the first and second group of DM-RSports. In other aspects, the UE may assume that the QCL configurationapplies to the QCL assumptions for the first group of DM-RS ports, andthat a default QCL configuration applies to the QCL assumptions for thesecond group of DM-RS ports.

In certain aspects, the UE may determine QCL assumptions for the DM-RSport groups based on a cell identification (cell ID). For instance, theUE may be connected to a TRP having a certain cell ID as configured viaRRC signaling. If the cell ID provided in a TCI state is the same as thecell ID provided in the RRC signaling, the QCL configuration provided inthe TCI state is applied to the first DM-RS port group, and a defaultQCL configuration is applied to the second DM-RS port group. In otheraspects, if the cell ID provided in the TCI state is different from thecell ID provided in the RRC signaling, the QCL configuration provided inthe TCI state is applied to the second DM-RS port group, and a defaultQCL configuration is applied to the first DM-RS port group.

In certain aspects, the UE may report its capability of supporting DM-RSport groups with different QCL assumptions to the BS. Based on thisreporting, higher-layer signaling may provide a maximum number ofsupported DM-RS port groups to the UE. In aspects, the BS may providethe UE with an indication of the maximum number of supported DM-RS portgroups. The UE may determine the payload size of downlink controlsignaling (e.g., DCI) based at least in part on the configured maximumnumber of supported DM-RS port groups. The UE may also determine how toapply the QCL assumptions included in the one or more TCI state(s) basedon the maximum number of supported DM-RS port groups as furtherdescribed herein.

As examples, if the maximum number of supported DM-RS port groups is setto 1, and one QCL assumption is provided in the TCI state(s), then theUE applies the QCL configuration to the sole DM-RS port groupconfigured. If the maximum number of supported DM-RS port groups is setto 1, and two QCL assumptions are provided in the TCI state(s), then theUE may assume the first QCL configuration applies to the sole DM-RS portgroup configured. If the maximum number of supported DM-RS port groupsis set to 1, and two QCL assumptions are provided in the TCI state(s),then the UE may apply the QCL assumption with a cell ID and bandwidthpart (BWP) ID that matches the cell ID and BWP ID of the DM-RS portgroup.

As other examples, if the maximum number of supported DM-RS port groupsis set to 2, only one DM-RS port group is configured, and one QCLassumption is provided in the TCI state(s), then the UE applies the QCLassumption to the configured DM-RS port group. In other aspects, if themaximum number of supported DM-RS port groups is set to 2, only oneDM-RS port group is configured, and one QCL assumption is provided inthe TCI state(s), then the UE applies the QCL assumption to the firstDM-RS port group, if the QCL assumption is from the first QCLconfiguration, or applies the QCL assumption to the second DM-RS portgroup, if the QCL assumption is from the second QCL configuration.Otherwise, the UE applies a default QCL assumption to the DM-RS portgroup.

In certain aspects, if the maximum number of supported DM-RS port groupsis set to 2, only one DM-RS port group is configured, and two QCLassumptions are provided in the TCI state(s), then the UE may apply theQCL assumption to the first DM-RS port group, if the QCL assumption isfrom the first QCL configuration, or the UE may apply the QCL assumptionto the second DM-RS port group, if the QCL assumption is from the secondQCL configuration. In other aspects, if the maximum number of supportedDM-RS port groups is set to 2, only one DM-RS port group is configured,and two QCL assumptions are provided in the TCI state(s), then the UEmay apply the QCL assumption with a cell ID and BWP ID that matches thecell ID and BWP ID of the corresponding DM-RS port group.

As further examples, if the maximum number of supported DM-RS portgroups is set to 2, two DM-RS port groups are configured, and only oneQCL assumption is provided in the TCI state(s), then the UE may applythe same QCL assumption to both groups. In other aspects, if the maximumnumber of supported DM-RS port groups is set to 2, two DM-RS port groupsare configured, and only one QCL assumption is provided in the TCIstate(s), then the UE may apply the QCL assumption to the correspondingDM-RS port group and apply a default QCL assumption to the other DM-RSport group.

In aspects, the maximum number of supported DM-RS port groups may alsobe indicated by a maximum number of QCL configurations per DLtransmissions. That is, the maximum number of QCL configurations per DLtransmissions may be used as higher layer signaling and provided to theUE in determining how to apply the QCL assumptions as described herein.

FIG. 12 illustrates a communications device 1200 (such as a BS 110 or aUE 120) that may include various components (e.g., corresponding tomeans-plus-function components) configured to perform operations for thetechniques disclosed herein, such as the operations illustrated in FIGS.9 and 10 . The communications device 1200 includes a processing system1202 coupled to a transceiver 1208 (e.g., a transmitter and/orreceiver). The transceiver 1208 is configured to transmit and receivesignals for the communications device 1200 via an antenna 1210, such asthe various signal described herein. The processing system 1202 may beconfigured to perform processing functions for the communications device1200, including processing signals received and/or to be transmitted bythe communications device 1200.

The processing system 1202 includes a processor 1204 coupled to acomputer-readable medium/memory 1212 via a bus 1206. In certain aspects,the computer-readable medium/memory 1212 is configured to storeinstructions that when executed by processor 1204, cause the processor1204 to perform the operations illustrated in FIGS. 9 and 10 , or otheroperations for performing the various techniques discussed herein.

In certain aspects, the processing system 1202 further includes atransmit/receive component 1214 for performing the operationsillustrated in FIGS. 9 and 10 . Additionally, the processing system 1202includes a generating component 1216 for performing the operationsillustrated in FIGS. 9 and 10 . Additionally, the processing system 1202includes an obtaining component 1218 for performing the operationsillustrated in FIGS. 9 and 10 . The transmit/receive component 1214,generating component 1216, and obtaining component 1218 may be coupledto the processor 1204 via bus 1206. In certain aspects, thetransmit/receive component 1214, generating component 1216, andobtaining component 1218 may be hardware circuits. In certain aspects,the transmit/receive component 1214, generating component 1216, andobtaining component 1218 may be software components that are executedand run on processor 1204.

The methods disclosed herein comprise one or more steps or actions forachieving the methods. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover a, b, c,a-b, a-c, b-c, and a-b-c, as well as any combination with multiples ofthe same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b,b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language of the claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedthroughout this disclosure that are known or later come to be known tothose of ordinary skill in the art are expressly incorporated herein byreference and are intended to be encompassed by the claims. Moreover,nothing disclosed herein is intended to be dedicated to the publicregardless of whether such disclosure is explicitly recited in theclaims. No claim element is to be construed under the provisions of 35U.S.C. § 112(f) unless the element is expressly recited using the phrase“means for” or, in the case of a method claim, the element is recitedusing the phrase “step for.”

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software component(s)and/or module(s), including, but not limited to a circuit, anapplication specific integrated circuit (ASIC), or processor. Generally,where there are operations illustrated in figures, those operations mayhave corresponding counterpart means-plus-function components.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device (PLD),discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

If implemented in hardware, an example hardware configuration maycomprise a processing system in a wireless node. The processing systemmay be implemented with a bus architecture. The bus may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system and the overall design constraints.The bus may link together various circuits including a processor,machine-readable media, and a bus interface. The bus interface may beused to connect a network adapter, among other things, to the processingsystem via the bus. The network adapter may be used to implement thesignal processing functions of the PHY layer. In the case of a userequipment 120 (see FIG. 1 ), a user interface (e.g., keypad, display,mouse, joystick, etc.) may also be connected to the bus. The bus mayalso link various other circuits such as timing sources, peripherals,voltage regulators, power management circuits, and the like, which arewell known in the art, and therefore, will not be described any further.The processor may be implemented with one or more general-purpose and/orspecial-purpose processors. Examples include microprocessors,microcontrollers, DSP processors, and other circuitry that can executesoftware. Those skilled in the art will recognize how best to implementthe described functionality for the processing system depending on theparticular application and the overall design constraints imposed on theoverall system.

If implemented in software, the functions may be stored or transmittedover as one or more instructions or code on a computer readable medium.Software shall be construed broadly to mean instructions, data, or anycombination thereof, whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Computer-readable media include both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. The processor may beresponsible for managing the bus and general processing, including theexecution of software modules stored on the machine-readable storagemedia. A computer-readable storage medium may be coupled to a processorsuch that the processor can read information from, and write informationto, the storage medium. In the alternative, the storage medium may beintegral to the processor. By way of example, the machine-readable mediamay include a transmission line, a carrier wave modulated by data,and/or a computer readable storage medium with instructions storedthereon separate from the wireless node, all of which may be accessed bythe processor through the bus interface. Alternatively, or in addition,the machine-readable media, or any portion thereof, may be integratedinto the processor, such as the case may be with cache and/or generalregister files. Examples of machine-readable storage media may include,by way of example, RAM (Random Access Memory), flash memory, ROM (ReadOnly Memory), PROM (Programmable Read-Only Memory), EPROM (ErasableProgrammable Read-Only Memory), EEPROM (Electrically ErasableProgrammable Read-Only Memory), registers, magnetic disks, opticaldisks, hard drives, or any other suitable storage medium, or anycombination thereof. The machine-readable media may be embodied in acomputer-program product.

A software module may comprise a single instruction, or manyinstructions, and may be distributed over several different codesegments, among different programs, and across multiple storage media.The computer-readable media may comprise a number of software modules.The software modules include instructions that, when executed by anapparatus such as a processor, cause the processing system to performvarious functions. The software modules may include a transmissionmodule and a receiving module. Each software module may reside in asingle storage device or be distributed across multiple storage devices.By way of example, a software module may be loaded into RAM from a harddrive when a triggering event occurs. During execution of the softwaremodule, the processor may load some of the instructions into cache toincrease access speed. One or more cache lines may then be loaded into ageneral register file for execution by the processor. When referring tothe functionality of a software module below, it will be understood thatsuch functionality is implemented by the processor when executinginstructions from that software module.

Also, any connection is properly termed a computer-readable medium. Forexample, if the software is transmitted from a website, server, or otherremote source using a coaxial cable, fiber optic cable, twisted pair,digital subscriber line (DSL), or wireless technologies such as infrared(IR), radio, and microwave, then the coaxial cable, fiber optic cable,twisted pair, DSL, or wireless technologies such as infrared, radio, andmicrowave are included in the definition of medium. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Thus, in some aspects computer-readable media maycomprise non-transitory computer-readable media (e.g., tangible media).In addition, for other aspects computer-readable media may comprisetransitory computer-readable media (e.g., a signal). Combinations of theabove should also be included within the scope of computer-readablemedia.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer-readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein and illustrated in FIGS. 9 and 10 .

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

The invention claimed is:
 1. A method of wireless communication by abase station (BS), comprising: transmitting signaling of a valueindicating a maximum number of supported demodulation reference signal(DM-RS) port groups to at least one user equipment (UE); transmittingquasi-colocation (QCL) information indicating a first QCL assumption fora first group of DM-RS ports and a second QCL assumption for a secondgroup of DM-RS ports; and transmitting downlink control information(DCI) indicating a first transmission configuration indicator (TCI)state associated with the first QCL assumption and a second TCI stateassociated with the second QCL assumption to the at least one UE for usein processing one or more transmission associated with at least one ofthe first group of DM-RS ports or the second group of DM-RS ports,wherein the DCI has a payload size based at least in part on the maximumnumber of supported DM-RS port groups.
 2. The method of claim 1, whereineach of the first TCI state and the second TCI state comprises a QCLconfiguration.
 3. The method of claim 2, wherein transmitting the QCLinformation comprises transmitting the first TCI state and the secondTCI state via control signaling including a radio resource control (RRC)element.
 4. The method of claim 1, wherein the value indicating themaximum number of supported DM-RS port groups is transmitted to the atleast one UE via at least one of a RRC element or a MAC element.
 5. Themethod of claim 1, wherein the maximum number of supported DMRS groupsis determined based on, receiving from the at least one UE, a UEcapability of supporting DM-RS port groups with different QCLassumptions.
 6. A method of wireless communication by a user equipment(UE), comprising: obtaining signaling of a value indicating a maximumnumber of supported demodulation reference signal (DM-RS) port groups;obtaining quasi-colocation (QCL) information indicating a first QCLassumption for a first group of DM-RS ports and a second QCL assumptionfor a second group of DM-RS ports; obtaining downlink controlinformation (DCI) indicating a first transmission configurationindicator (TCI) state associated with the first QCL assumption and asecond TCI state associated with the second QCL assumption, wherein theDCI has a payload size based at least in part on the maximum number ofsupported DM-RS port groups; and receiving transmissions associated withthe first group of DM-RS ports and the second group of DM-RS ports basedon the DCI.
 7. The method of claim 6, wherein each of the first TCIstate and the second TCI state comprises a QCL configuration.
 8. Themethod of claim 7, wherein obtaining the QCL information comprisesobtaining the first TCI state and the second TCI state via controlsignaling including a radio resource control element.
 9. The method ofclaim 6, further comprising reporting a capability of supporting DM-RSport groups with different QCL assumptions, wherein the maximum numberof supported DM-RS port groups is based on the reporting.
 10. The methodof claim 6, wherein each of the first TCI state and the second TCI statehas a single QCL configuration.
 11. The method of claim 10, whereinreceiving transmissions comprises applying the QCL configurationsassociated with the first and second QCL assumptions.
 12. The method ofclaim 6, wherein: the QCL information includes a cell identification(ID); and receiving the transmissions comprises applying the QCLinformation to one of the first group or second group of DM-RS portsassociated with a same cell ID as the cell ID of the QCL information.13. An apparatus for wireless communication, comprising: at least onememory storing computer-executable instructions; and at least oneprocessor coupled to the at least one memory, the at least one processorbeing configured to execute the computer-executable instructions andcause the apparatus to: transmit signaling of a value indicating amaximum number of supported demodulation reference signal (DM-RS) portgroups to at least one user equipment (UE); transmit quasi-colocation(QCL) information indicating a first QCL assumption for a first group ofDM-RS ports and a second QCL assumption for a second group of DM-RSports; and transmit downlink control information (DCI) indicating afirst TCI state associated with the first QCL assumption and a secondTCI state associated with the second QCL assumption to the at least oneUE for use in processing one or more transmission associated with atleast one of the first group of DM-RS ports or the second group of DM-RSports, wherein the DCI has a payload size based at least in part on themaximum number of supported DM-RS port groups.
 14. An apparatus forwireless communication, comprising: at least one memory storingcomputer-executable instructions; and at least one processor coupled tothe at least one memory, the at least one processor being configured toexecute the computer-executable instructions and cause the apparatus to:obtain signaling of a value indicating a maximum number of supporteddemodulation reference signal (DM-RS) port groups; obtainquasi-colocation (QCL) information indicating a first QCL assumption fora first group of DM-RS ports and a second QCL assumption for a secondgroup of DM-RS ports; obtain downlink control information (DCI)indicating a first TCI state associated with the first QCL assumptionand a second TCI state associated with the second QCL assumption,wherein the DCI has a payload size based at least in part on the maximumnumber of supported DM-RS port groups; and receive transmissionsassociated with the first group of DM-RS ports and the second group ofDM-RS ports based on the DCI.
 15. The apparatus of claim 13, wherein themaximum number of supported DMRS groups is determined based on a UEcapability, received from the at least one UE, of supporting DM-RS portgroups with different QCL assumptions.
 16. The apparatus of claim 14,wherein the at least one processor is further configured to cause theapparatus to: report a capability of supporting DM-RS port groups withdifferent QCL assumptions, wherein the maximum number of supported DM-RSport groups is based on the capability.